1. Field of the Invention
This invention concerns synthetic sweeteners. More particularly, it concerns a new group of dihydrochalcone compounds and their use as sweeteners for edible compositions such as foodstuffs.
2. Discussion of the Prior Art
Dihydrochalcones are compounds having a ##STR2## basic structure. Various examples of dihydrochalcones have been known since the 1930s. The members of this class of dihydrochalcones vary from one another by the nature and placement of substituents on the aromatic rings.
In 1963 it was discovered that some, but by no means all, of the dihydrochalcones are sweet (Horowitz and Gentili, U.S. Pat. No. 3,087,821, issued Apr. 30, 1963). The earliest examples of sweet dihydrochalcones were derived from naturally occurring flavanones having bulky saccharide residues attached at position 4. More recently, several sweet dihydrochalcones having smaller and simpler substituents at their 4 position have been disclosed. Such disclosures include Rizzi, U.S. Pat. No. 3,855,301, issued Dec. 17, 1974; Rizzi, U.S. Pat. No. 3,751,270, issued Aug. 7, 1973; Farkus et al., U.S. Pat. No. 3,956,375, issued May 11, 1976; Crosby et al., U.S. Pat. No. 3,974,299, issued Aug. 10, 1976; Crosby et al., U.S. Pat. No. 3,976,790, issued Aug. 24, 1976; Crosby et al., U.S. Pat. No. 4,055,678, issued Oct. 25, 1977 and U.S. Ser. No. 964,211, filed by Crosby et al. on Dec. 1, 1978.
Among the prior art references, the last mentioned patents and application of Crosby et al. disclose compounds which are considered to be structurally closest to the present materials. The prior art compounds have substituents in the 2, 6 and 4' positions which are the same as those of the present compounds. Importantly, however, these references do not show or suggest the alpha amino acid 4 position substituent which the present compositions require. All employ groups which are chemically far different from the present alpha amino acid.
If there is one fact that may be derived from the prior art, it is that no underlying taste-structure relationship has been developed or proved for the dihydrochalcones. Changes which are chemically minor on their face may have a major effect on taste properties. The taste/structure relationship still is largely empirical and not predictable.